TVIS?

[JMR_AW11]

On the UK 4A-GE ECU for both AE86 and AW11 MR2, Toyota employ a little trick in the ECU program code to add some kick to the TVIS.

When the rpm exceeds the TVIS threshold the ECU starts a little delay counter. This counter adds a delay to allow the TVIS flaps to open, once the counter finishes the ECU suddenly adds 3 degrees of ignition advance to the timing!

This was maybe a marketing ploy to help sell the benefits of TVIS. i.e. some of the kick is really the sudden ignition timing change!

if you remove the TVIS mechanicals you will still get the 3 degree step in timing at the TVIS rpm.

It is actually quite annoying as this means the engine is starved of optimum ignition timing below the TVIS point (by maybe 3 degrees!)

Just to get that kick...